Adding to the growing body of literature demonstrating the feasibility of correcting lethal genetic diseases before birth, researchers at Children’s Hospital of Philadelphia (CHOP) have used DNA base editing in a prenatal mouse model to correct a lysosomal storage disease known as Hurler syndrome. Using an adenine base editor delivered in an adeno-associated viral vector, the researchers corrected the single base mutation responsible for the condition, which begins before birth and affects multiple organs, with the potential to cause death in childhood if untreated.